Electron discharge device



1955 J. M. CONNELLY 3,202,860

ELECTRON DISCHARGE DEVICE Filed Feb. 15, 1961 INVENTOR. JOSEPH M. CONNELLY AT TO RN EY United States Patent 3,292,360 ELECTRGN DKSQHARGE DEVICE doseph M. Connelly, Gwensboro, Ky., assignor to General Electric Company,-a corporation'of New York Filed Feb. 13, 1961, Ser. No. 89,021

3 Claims. (Cl. 313-244) This invention relates to electron discharge devices and more particularly to such devices of improved ceramic and metal construction and to novel methods of manufacture thereof.

In certain types of electron discharge devices, the envelope for the devices comprises a plurality of stacked alternating layers of insulative wall sections and metallic terminal members. Such devices have heretofore been assembled by stacking the components of the envelope in a suitable array in an evacuation chamber, with a suitable solder ring positioned'between each of the adjacent elements. The chamber is evacuated by any suitable means, and at the same time the interior of the envelope is also evacuated. While in the evacuated chamber, the device is subjected to heat, which causes the solder rings to melt and flow, and, upon being cooled, the adjacent components of the envelope are thereby bonded and sealed together by the solder.

I have found it to be desirable to provide a means for fast removal of evolved gases from the interior of the stacked array and, during the heating operation for the reason that prompt removal of evolved gases while the entire device is atelevated temperature prevents or mini mizes adsorption of gases on the inner surfaces of the elements of the array and because failure to promptly remove such evolved gases permits the development of a pressure differential between the inside of the array and the evacuated chamber that causes seal discontinuities in the form of blow holes when the solder material becomes liquid during sealing. Furthermore, I have observed that failure to remove; promptly gases evolved from metal parts during sealing can cause deleterious conductive films to be formed over internal insulator surfaces. This action may occur during the sealing of complete electron discharge devices and more particularly during sealing of sub-sections of'elect-ron discharge devices or similarly enclosed envelope structures usable in assemblies other-than electrondischarge devices, as for example in vacuum capacitors, resistors, or the like.

It is accordingly the primary'object of the present invention to provide a new and improved electron discharge device.

It is another object of the invention to provide a new and improved electron discharge device having means to facilitate the removal of the above-mentioned gases.

It is another object of the present invention to provide a new and improved method of effecting the evolution and removal of occluded gases from an envelope and its contents and sealing and evacuating the envelope by means of a single operational step.

Still another object of the present invention is to provide new and improved methods of manufacturing evac uated devices whereby substantial economies in manufacturing effort, time and materials and improved qualities are realized.

Further objects and advantages of the present invention Will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

Briefly stated, and in accordance with one aspect of the invention, the abutting surface of one of the components of the envelope at which the component is to 3,Z@Z,89 Patented A11 24, 1965 "ice ' uated chamber, and when the solder ring melts and begins to flow, a portion of the solder will flow into the groove, thereby sealing the groove. When the device is then cooled, the gases will have been removed from the interior portions of the envelope and a tight seal will be effected between the interior and exterior portions of the envelope.

For a better understanding of the invention, reference should be had to the accompanying drawing, in which:

FIG. 1 is a longitudinal cross-sectional view of an electron discharge device embodying the features of the invention; and

FIG. 2 shows an exploded view of the electron discharge device.

Referring now to the drawing, my invention is dis.- closed as embodied in an electron discharge device of ceramic and metal construction generally of the type described and claimed in U.S. Patent No. 2,923,847, of C. G. Childs and J. M. Connelly, patented February2, 1960 and assigned to the assignee of the present application. It will, of course, be understood that the invention may also be embodied in other types of evacuated devices, such as, for example, vacuum capacitors,-resis tors or integrated module's comprising assemblies of .electron discharge devices and capacitors, resistors, inductances and associated circuit elements, the present description as appliedto the ceramic and metal electronic discharge device being exemplary only. The electron'discharge device 1 may comprise, in coaxial array, an anode button 2, a generally cylindrical grid insulator 3, aigrid ring 4 and grid 4' subassembly, a cathode insulator 5, a cathode assembly 6, including a cathode ring 7 and a heater insulator 8. The lead pins 9 to which a filamentary heater 11 can be connectedcomplete the envelope structure.- The anode 2, the grid ring 4, and the cathode ring 7 may bemade of any suitable conducting and gas gettering material such as titanium, while the grid insulator 3, the cathode insulator 5, and the heater insulator 8 may be made of any suitable insulative material, such as an insulating ceramic material. i j It willbe appreciated that the envelope of the electron discharge device 1 formed by the stacking and'bonding together of the above-described component encloses a space Within which an electron discharge is maintainable between the active electrode elements.

In accordance with a principal feature of the invention, and to facilitate exhaust and sealing of the discharge space during assembly of the device, the cathode'ring 7 is provided on its upper and lower surfaces with a plurality of radially extending grooves 10, each of which .extends and communicates between the interior portion of the envelope to be evacuated and the exterior of the envelope. ously described components that form the envelope of the electron discharge device 1 are arranged to be stacked and held by a suitable jig (not shown) in their proper array, and a solder disk or ring, as at 20, is positioned between each of the abutting surfaces of the adjacent ones of the components of the array. The abutting surfaces may be planar, as shown, or may be formed in any complementary surfaces, so as to form a smooth joint.

While the device is being evacuated by any suitable means such as, for example, by being placed within an evacuation chamber (not shown), the device is heated to When the device is being assembled, the previ-' a cause the solder rings to melt and flow and thus spread between contiguous surfaces of the adjacent ones of these components. However, while the device is being heated to the temperature sufiicient to cause the solder rings to melt, gases may be evolved on the interior of the envelope which, if allowed to remain within the envelope, would have the deleterious effects hereinabove described. However, since the device is still positioned within the evacuation enclosure during this operation, these evolved gases are readily withdrawn from the interior of the device 1 through the grooves of the invention and thus removed from the device 1. When the solder rings melt and begin to flow, the molten solder also flows into the grooves 10, thus sealing the grooves 10 as well as effecting an hermetic bond of the adjacent components. When the device is allowed to cool, the adjacent components are then permanently hermetically bonded together and the grooves 10 are permanently sealed.

In the embodiment described herein, the cathode ring 7 is shown provided with six radially extending grooves '10, the grooves 16 being of sufficient length to extend be tween the interior and exterior portions of the envelope of the device 1. Three grooves 10 are provided on each abutting surface of the cathode ring 7, the grooves 10 beingequiangularly spaced around the circumference of the cathode ring 7.

Obviously, the invention is not limited to providing six grooves 10 on one or both of the abutting surfaces of the cathode ring 7, but any suitable number of grooves 10 may be located on any of the abutting surfaces of any of the other components, such as the grid ring, which when assembled form the envelope of the device 1. Regardless of which abutting surface the grooves 10 are positioned upon, the solder ring which provides bonding between that abutting surface and the abutting surface of the adjacent component will also seal the grooves 10 when the temperature of the device 1 is raised sufiiciently high to cause the solder rings to melt and flow. Thus, any gases evolved on the interior of the device 1 when the device 1 is heated will readily and promptly be removed through the grooves 10 before the solder seals the grooves 10.

Also, the method of the invention is not limited to any particular manner of forming the evacuation grooves 10; for example, the grooves may be formed by embossing,

etching, scratching, or any other suitable manner.

While the invention is thus disclosed and a specific embodiment shown, the invention is not limited to this shown, but may instead be used in any device in which abutting surfaces are bonded in the manner described. The invention is also not limited to the specific shape or radial form of evacuation grooves as shown, but instead, any manner or form of evacuation grooves, such as spiral or skewed grooves which will provide communication between the interior and exterior of the device will be suificient. It is desired instead that the invention be limited only by the appended claims.

What is claimed as new and desired to secure by Letters Patent of the United States is:

1. The method of evacuating and sealing an electron discharge device having an envelope comprised of two members each having an abutting surface, said members being joined at said abutting surfaces, comprising the steps of providing one of said abutting surfaces with at least one groove therein communicating between the interior and exterior of the envelope, disposing a thermally operative sealing means between said abutting surfaces, and heating said envelope to a predetermined temperature range while being evacuated, wherein said sealing means is rendered effective for joining said members and closing said grooves while permitting evolved gases to be withdrawn from the interior of the device before the predetermined temperature range is reached.

2. A planar electrode electron discharge device having an envelope comprising a cylindrical insulating member having an abutting surface, a cylindrical electrically conductive member having an abutting surface, at least one evacuation groove in the abutting surface of said conductive member, said groove communicating between the interior and exterior of said envelope and means for joining said cylindrical members at said abutting surfaces comprising a solder ring positioned between said abutting surfaces to fill and seal said groove. 3. The device defined in claim 2 wherein said groove is hollow, whereby interference with the filling of said groove with solder during the sealing operation is minimized.

References Cited by the Examiner UNITED STATES PATENTS 2,210,131 8/40 Scharfnagel 313-244 2,680,824 6/54 Beggs 313-250 2,752,532 6/56 Dussaussoy et al. 316-19 2,792,271 5/57 Beggs 31e 19 2,950,412 8/60 Albert 313-250 JOHN W. HUCKERT, Primary Examiner.

RALPH G. NILSON, JAMES D. KALLAM, Examiners. 

1. THE METHOD OF EVACUATING AND SEALING AN ELECTRON DISCHARGE DEVICE HAVING AN ENVELOPE COMPRISED OF TWO MEMBERS EACH HAVING AN ABUTTING SURFACE, SAID MEMBERS BEING JOINED AT SAID ABUTTING SURFACES, COMPRISING THE STEPS OF PROVIDING ONE OF SAID ABUTTING SURFACES WITH AT LEAST ONE GROOVE THEREIN COMMUNICATING BETWEEN THE INTERIOR AND EXTERIOR OF THE ENVELOPE, DISPOSING A THERMALLY OPERATIVE SEALING MEANS BETWEEN SAID ABUTTING SURFACES, AND HEATING SAID ENVELOPE TO A PREDETERMINED TEMPERATURE RANGE WHILE BEING EVACUATED, WHEREIN SAID SEALING MEANS IS RENDERED EFFECTIVE FOR JOINING SAID MEMBERS AND CLOSING SAID GROOVES WHILE PERMITTING EVOLVED GASES TO BE WITHDRAWN FROM THE INTERIOR OF THE DEVICE BEFORE THE PREDETERMINED TEMPEATURE RANGE IS REACHED. 